ROCKVILLE, Md. — Maryland Reps. Donna Edwards and Chris Van Hollen faced off for the first time Sunday, showcasing sharply different styles as they vie for the Democratic nomination for Senate.

Speaking here in an office park at a forum hosted by the National Organization for Women, the two candidates running to replace retiring Democratic Sen. Barbara A. Mikulski touched on issues of women's health, economic inequality, trade and violence. Van Hollen, a white man, and Edwards, a black woman, spoke before a women's group after a week in which racial tensions in Baltimore overwhelmed the national conversation, a fact of which both were keenly aware.

Van Hollen kicked off his remarks by pointing to his efforts to seek equality for all — women, disabled people, gays. While he's not a member of any of those groups, he did so because it was the right thing to do, he said.

"I don't have a severe disability, people in my immediate family don't have a severe disability," Van Hollen said about the ABLE Act, a bill he co-sponsored in 2014 to help families with children with disabilities. "But they asked me to be the lead Democratic sponsor, and we got that done. ... All of these issues that we're going to be talking about today, that NOW has fought for for so long, in my view are issues of human rights and equal rights, and we need to be in that fight together."

Edwards, on the other hand, drew on her personal story as a black woman and a single mother, saying her firsthand experience dealing with many of the issues made her uniquely qualified.

"I think it's really important that when we’re talking about equal pay for equal work that we know there’s a woman sitting at the table who’s experienced unequal pay," Edwards said. In discussions about poverty and unequal access to good education in different areas of the state, she said, "I think it’s important to have somebody around the table like me who understands what that discussion is all about."

They took divergent paths when explaining why he or she would be the best candidate for the job. Van Hollen, the top Democrat on the House Budget Committee and with a seat in leadership, touted his experience in Congress and the state Legislature before that. Edwards, who first came to Congress in 2008, focused instead on her work as a community activist before she was elected.

"I think sometimes as members of Congress we actually sometimes overstate our importance and understate the importance of grass-roots activists around the country," she said.

The clash took place in a carpeted room in an office building, with some 75 men and women seated on plastic chairs set up in a semicircle. Edwards and Van Hollen sat behind a desk on either side of the moderator, who timed their comments with her cellphone. When their time was up, the moderator's alarm would ring until the candidate stopped talking.

Their contrast in tone was stark. Edwards was combative, Van Hollen was wonky.

It was Edwards who took the first jab at her opponent, criticizing him for his professed willingness to accept a budget compromise that included cuts to Social Security.

"I think here is where there is and has been, frankly, a fundamental difference between myself and Chris Van Hollen. ... When it came time to cut a deal, that was part of a budget deal, Mr. Van Hollen was willing to consider, those are his own words, cuts to Social Security and Medicare," Edwards said. "I think that is unacceptable. Social Security and Medicare are bedrock fundamental principles of the Democratic Party."

Van Hollen defended himself on Social Security, but never hit back at Edwards.

"I actually led the effort to convince the president not to put the chained CPI proposal in his second budget. At the same time, frankly, I persuaded him not to put a cut in federal employee benefits in his budget," Van Hollen said, noting his high ratings with retirement groups.

Even after the forum, Van Hollen ducked his head and demurred when asked by CQ Roll Call about the fact that she had gone after him, saying he had said all he had to say during the debate.

Van Hollen and Edwards are the only two Democrats running so far, but in a state where the party has a significant advantage, more could enter. Former Lt. Gov. Kathleen Kennedy Townsend has said she is considering it, as has Rep. Elijah E. Cummings, who has been a constant media presence after unrest broke out in his hometown of Baltimore.

Rockville is located squarely in Van Hollen's Montgomery County-based 8th District, and his supporters made it clear it was his home turf. "Van Hollen for Maryland" signs lined the walkway to the event, and about a dozen volunteers stood outside, holding signs and handing out bumper stickers. There were no signs for Edwards, who had far less of an organizational presence.

After the debate's conclusion, Edwards left quickly, while Van Hollen lingered for some 20 minutes, chatting with supporters and posing for pictures with some holding signs. As he made his way out, a woman handed him her baby to pose for a picture, and Van Hollen gave the youngster a kiss on the head.

The primary may be 11 months away, but campaign season is clearly in full swing.